<form class="pictureForm" id="pictureForm" name="pictureForm" method="post" action="" enctype="multipart/form-data" >
    <div>
        <label>Selecciona tu imagen</label><br><br>
        
        ><input type="file" id="file" name="file" >
   </div>
    <input type="hidden" name="pictureForm" id="pictureForm" value="hola"> <!--palabra de seguridad-->
    <a href="#" class="boton" onClick="document.getElementById('pictureForm').submit();">Enviar Imagen</a>
</form>
<div class='nota'>
        tipo admitido:jpg,jpeg,png,gif<br>
        tamaño maximo:250kB<br>
</div>